2023 Cambridge IAL Economics (9708) 模擬試題連答案詳解

To calculate the Marginal Revenue Product (MRP) of the 4th worker:

1. **Identify the Marginal Physical Product (MPP)** of the 4th worker:
\(\text{MPP} = \text{TPP}_4 - \text{TPP}_3\)
\(\text{MPP} = 31 - 24 = 7\) kg per hour

2. **Calculate the MRP**:
Since the firm operates in a perfectly competitive product market, the Marginal Revenue (MR) is equal to the market price (P), which is \(\$12\).
\(\text{MRP} = \text{MPP} \times P\)
\(\text{MRP} = 7 \times \$12 = \$84\)

- **1 mark** for identifying or calculating the Marginal Physical Product (MPP) of the 4th worker as \(7\) kg (or showing the working \(31 - 24\)).
- **1 mark** for the correct final calculation of \(\$84\) (accept \(84\)).

*Note: Award full 2 marks for the correct final answer of \(\$84\) (or \(84\)) with or without working.*

To calculate the Marginal Revenue Product (MRP) of the 4th worker:

1. **Identify the Marginal Physical Product (MPP)** of the 4th worker:
\(\text{MPP} = \text{TPP}_4 - \text{TPP}_3\)
\(\text{MPP} = 31 - 24 = 7\) kg per hour

2. **Calculate the MRP**:
Since the firm operates in a perfectly competitive product market, the Marginal Revenue (MR) is equal to the market price (P), which is \(\$12\).
\(\text{MRP} = \text{MPP} \times P\)
\(\text{MRP} = 7 \times \$12 = \$84\)

- **1 mark** for identifying or calculating the Marginal Physical Product (MPP) of the 4th worker as \(7\) kg (or showing the working \(31 - 24\)).
- **1 mark** for the correct final calculation of \(\$84\) (accept \(84\)).

*Note: Award full 2 marks for the correct final answer of \(\$84\) (or \(84\)) with or without working.*

When individuals consume public transport, they generate external benefits (positive externalities) to third parties who are not directly involved in the transaction. These benefits include reduced traffic congestion, shorter travel times for other road users, and lower carbon emissions. In a free market, individuals only consider their private marginal benefits (PMB) and ignore these external benefits, meaning that the social marginal benefit (SMB) is greater than the PMB. This results in the underconsumption of public transport and allocative inefficiency. By providing a subsidy to public transport operators, the government lowers the costs of production, which shifts the supply curve to the right and reduces the fares for passengers. This financial incentive encourages more individuals to switch from private cars to public transport, increasing consumption closer to the socially optimal level where SMB equals social marginal cost (SMC).

Award up to 3 marks as follows: 1 mark for defining or explaining positive externalities in the context of public transport (e.g., benefits to third parties such as reduced road congestion or pollution). 1 mark for explaining that a free market leads to underconsumption because consumers only consider private benefits (PMB < SMB). 1 mark for explaining how a subsidy lowers fares/costs and increases consumption towards the socially optimal level.

A national minimum wage is a legally mandated price floor in the labour market. When the government increases this minimum wage, it directly raises the variable costs of production for firms that employ low-skilled workers. To maintain their profit margins, firms may respond in two ways that create a policy conflict. First, they may pass these higher wage costs onto consumers in the form of higher prices for their goods and services, leading to cost-push inflation. Second, to control their total expenditure, firms may reduce their demand for labour by laying off workers, freezing recruitment, or replacing labor with capital (automation). This reduction in employment opportunities increases the level of unemployment. Therefore, the government's attempt to support low earners through a higher minimum wage can conflict with its objectives of maintaining stable prices and low unemployment simultaneously.

Award up to 3 marks as follows: 1 mark for explaining how a higher minimum wage increases production costs for firms, leading to cost-push inflation as prices are raised. 1 mark for explaining how higher wage costs can cause firms to reduce their demand for labour, leading to job losses and higher unemployment. 1 mark for explaining the conflict between the two objectives (i.e., achieving one objective makes it harder to achieve the other).

A tradable pollution permit scheme corrects market failure by establishing a government-mandated limit (cap) on the total volume of emissions. Permits matching this cap are allocated or auctioned to firms. Since these permits are tradable, a market price for pollution is established. Firms with high abatement costs will buy permits, while those with low abatement costs will reduce emissions and sell their excess permits. This internalises the negative externality, shifting the marginal private cost (MPC) curve closer to the marginal social cost (MSC) curve, thereby reducing output to the allocatively efficient social optimum where \(MSC = MSB\). However, implementation is difficult because governments face imperfect information. If the cap is set too high, the permit price falls to zero, failing to incentivise emission reductions. If set too low, it overly restricts production, causing high prices and potentially leading to carbon leakage where firms relocate to countries with laxer regulations.

Up to 3 marks for explaining the correction of market failure: 1 mark for identifying that a cap is set and permits are traded. 1 mark for explaining that this creates a price for carbon / internalises the external cost. 1 mark for explaining the adjustment toward the socially optimal output level where MSC equals MSB. Up to 3 marks for analyzing an implementation difficulty: 1 mark for identifying a relevant difficulty (e.g. imperfect information in setting the cap, monitoring costs, carbon leakage). 2 marks for explaining how this difficulty undermines the policy's effectiveness.

Rapid economic growth is often driven by increases in aggregate demand (\(AD\)). If \(AD\) expands faster than the productive capacity of the economy (long-run aggregate supply), it leads to excess demand and shortages, causing demand-pull inflation and compromising price stability. Additionally, rapid growth is associated with rising national income. As consumer incomes rise, spending on imported consumer goods and services increases, especially if the marginal propensity to import is high. Furthermore, if domestic inflation rises due to the high growth, domestic exports become relatively more expensive and imports become relatively cheaper. This dual effect reduces net exports, deteriorating the current account balance and causing a conflict with the balance of payments objective.

Up to 3 marks for analyzing the conflict with price stability: 1 mark for identifying that growth shifts AD to the right. 1 mark for explaining how this creates demand-pull inflation (especially near full capacity). 1 mark for linking this to the erosion of price stability. Up to 3 marks for analyzing the conflict with the current account: 1 mark for identifying that higher incomes increase the demand for imports. 1 mark for explaining how inflation reduces export competitiveness. 1 mark for concluding how this deteriorates the current account balance.

1. **Initial Monopsony Equilibrium:**
- A monopsonist is the sole buyer of labour in a market and faces the market supply curve for labour, which is upward-sloping. This represents the Average Cost of Labour (ACL).
- To hire an additional worker, the firm must raise the wage for all workers, making the Marginal Cost of Labour (MCL) higher than the ACL at every level of employment above zero.
- The profit-maximising monopsonist employs labour where MCL = MRPL (Marginal Revenue Product of Labour), which determines the employment level \(Q_1\).
- The wage paid is determined by the labour supply curve (ACL) at \(Q_1\), which is \(W_1\). This wage is lower than both the MCL and the MRPL, representing the monopsonistic exploitation of labour.

2. **The Introduction of a Minimum Wage:**
- If a minimum wage \(W_{min}\) is set above \(W_1\), the firm can no longer pay a wage lower than \(W_{min}\).
- The labour supply curve (ACL) becomes perfectly elastic (horizontal) at \(W_{min}\) up to the point where it meets the original upward-sloping supply curve.
- Because the wage is constant over this range, the marginal cost of hiring an additional worker is simply equal to the minimum wage (MCL = ACL = \(W_{min}\)).

3. **New Equilibrium with Higher Employment and Wages:**
- The new MCL curve has a horizontal section at \(W_{min}\) and then jumps up to the original MCL curve once the horizontal minimum wage boundary is passed.
- To maximise profits under these new conditions, the firm equates the new MCL (which is \(W_{min}\)) with MRPL. This occurs at a higher level of employment, \(Q_2\).
- Therefore, the intervention successfully increases the wage from \(W_1\) to \(W_{min}\) and simultaneously expands employment from \(Q_1\) to \(Q_2\).

**Diagram (Up to 3 marks):**
- 1 mark for correctly labelled axes (Wage rate on the vertical axis, Quantity of labour on the horizontal axis) and correctly drawn, labelled MRPL, ACL (or SL), and MCL curves.
- 1 mark for showing the initial monopsony equilibrium at wage \(W_1\) and employment \(Q_1\), where MCL = MRPL.
- 1 mark for showing the effect of the minimum wage \(W_{min}\), including the horizontal portion of the new MCL and the resulting higher employment level \(Q_2\).

**Explanation (Up to 5 marks):**
- Up to 2 marks for explaining why the monopsonist originally restricts employment to \(Q_1\) and pays a wage \(W_1\) below the MRPL (explaining why MCL is above ACL).
- Up to 2 marks for explaining how the introduction of a minimum wage alters the ACL and MCL curves, making them perfectly elastic at \(W_{min}\) up to the original supply curve.
- 1 mark for explaining that the firm now equates the new MCL with MRPL, leading to an increase in employment to \(Q_2\) alongside the higher wage rate.

Industrial emissions create negative externalities of production, leading to a misallocation of resources where the marginal social cost (MSC) exceeds the marginal private cost (MPC). This leads to overproduction and deadweight welfare loss, representing market failure. Governments can intervene using either tradable pollution permits or indirect taxes to correct this. Tradable pollution permits work by capping the total allowable volume of emissions. The government issues a fixed number of permits, which firms can buy and sell in a market. Low-polluting firms can sell their excess permits, while highly polluting firms must purchase additional permits. This market mechanism establishes a price for emissions, incentivising firms to invest in cleaner, greener technologies to reduce costs. The primary advantage of this policy is quantity certainty; the government can guarantee that emissions will not exceed the set cap. However, the market price of permits can be highly volatile, creating uncertainty for business planning, and the administrative costs of monitoring emissions and managing the permit market can be exceptionally high. An indirect tax is levied on the polluting firm, ideally equal to the marginal external cost (MEC) at the socially optimum level of output. This tax increases the firm's private costs, shifting the supply curve upwards to align with the MSC curve. Consequently, the equilibrium price rises, and the quantity produced falls to the socially optimal level, eliminating the deadweight loss. The key advantage of a tax is price certainty, which allows firms to plan long-term investments with a stable cost structure, and it generates substantial tax revenue that the government can use to fund green infrastructure. However, the main disadvantage is quantity uncertainty. Because the government rarely has perfect information about the exact shape of the demand and MSC curves, setting the tax rate incorrectly will fail to achieve the socially optimum output. In evaluation, neither policy is universally superior; their effectiveness depends on specific economic goals and context. If a country must meet strict international environmental targets, tradable permits are more effective because they guarantee the quantity of emissions reduction. Conversely, if administrative capacity is limited, an indirect tax is preferable because it uses existing tax-collection structures and avoids price volatility. Ultimately, a combination of both, or a hybrid system with a permit price ceiling and floor, often provides the most effective policy framework.

AO1 Knowledge and Understanding and AO2 Analysis (7-8 marks): - 7 to 8 marks: Clear, detailed, and balanced explanation of both tradable pollution permits and indirect taxes. The candidate explains how both policies attempt to internalise the negative externalities of production to achieve the socially optimal allocation of resources. Key concepts such as marginal social cost (MSC), marginal private cost (MPC), and market-based incentives are accurately analysed. - 5 to 6 marks: Detailed explanation of one policy and a limited explanation of the other, or a moderate explanation of both policies with minor analytical gaps. - 3 to 4 marks: Limited explanation of both policies or a detailed explanation of only one policy. - 1 to 2 marks: Shows basic knowledge of pollution policies but lacks analytical depth. AO3 Evaluation (3-4 marks): - 3 to 4 marks: Formulates a well-supported and balanced comparative evaluation of both policies. Evaluates key trade-offs, such as certainty of quantity (permits) versus certainty of price (taxes), administrative costs, and information asymmetry. Concludes with a reasoned judgment on which policy is more effective under specific conditions. - 1 to 2 marks: Offers a simple, unstructured evaluative comment without deep comparative reasoning or a well-justified conclusion.

Short-run relationship: The Short-Run Phillips Curve (SRPC) shows an inverse trade-off between inflation and unemployment. When a government uses expansionary monetary or fiscal policy to boost Aggregate Demand (AD), firms increase production and hire more workers, reducing cyclical unemployment. However, this tightens the labor market, bids up wages, and increases demand-pull and cost-push inflation. Long-run relationship: In the long run, there is no trade-off between inflation and unemployment. The Long-Run Phillips Curve (LRPC) is vertical at the Natural Rate of Unemployment (NRU). If the government attempts to maintain unemployment below the NRU, workers eventually realize their real wages have been eroded by inflation. They demand higher nominal wages, which increases production costs for firms. Firms respond by cutting back employment, and unemployment returns to the NRU but at a higher rate of inflation. This shifts the SRPC outwards. Policy Comparison: Demand management policies (fiscal and monetary) are highly effective in the short run to eliminate cyclical unemployment. However, they are completely ineffective in the long run as they only create accelerating inflation without lowering unemployment. To reduce unemployment in the long run, governments must use structural, supply-side policies (such as education, training, and labor market deregulation) to lower the NRU.

Analysis of the Short-run Phillips Curve (Up to 3 marks): 1 mark for identifying the inverse relationship/trade-off between inflation and unemployment. 1 mark for explaining the transmission mechanism (e.g., AD increase leading to lower cyclical unemployment but higher wages/prices). 1 mark for referring to a downward-sloping SRPC. Analysis of the Long-run Phillips Curve (Up to 3 marks): 1 mark for identifying that there is no trade-off in the long run and the LRPC is vertical. 1 mark for explaining the role of inflationary expectations and real wage adjustments. 1 mark for explaining how the economy returns to the Natural Rate of Unemployment (NRU). Comparison of Policy Implications (Up to 2 marks): 1 mark for comparing the short-run effectiveness of demand management (effective for cyclical unemployment) with its long-run ineffectiveness (leads only to inflation). 1 mark for identifying that supply-side policies are required to reduce the NRU in the long run.

Introduction:
- Define sustainable economic growth (an increase in real GDP that can be maintained without causing significant inflationary or environmental problems).
- Define supply-side policies (actions aimed at increasing the productive capacity of the economy, e.g., education, infrastructure spending, deregulation) and monetary policies (manipulation of interest rates, money supply, and exchange rates by the central bank).

Analysis of Supply-Side Policies:
- Explain how interventionist supply-side policies (e.g., state-funded education/training, infrastructure investment) or market-based policies (e.g., tax cuts, deregulation, labor market reforms) shift the Long-Run Aggregate Supply (LRAS) curve to the right.
- Explain how a rightward shift in LRAS increases real national output (growth) while simultaneously lowering or stabilizing the price level, allowing for non-inflationary growth.
- Highlight benefits: unlike expansionary demand policies, supply-side growth resolves structural bottleneck problems and reduces cost-push inflationary pressures.

Limitations of Supply-Side Policies:
- Long time lags: education reforms or major infrastructure projects take years to yield productive results.
- High fiscal cost and opportunity cost, which could lead to government budget deficits and structural debt.
- Risk of policy failure: training programs might not match the future skills required by employers.

Analysis of Monetary Policy as an Alternative:
- Explain how monetary policy manages Aggregate Demand (AD). For example, contractionary monetary policy (raising interest rates) reduces consumer spending and investment, shifting AD to the left to control demand-pull inflation.
- Explain how expansionary monetary policy can stimulate investment and consumer spending to boost growth in the short run.

Limitations of Monetary Policy:
- Raising interest rates to control inflation can severely dampen investment, harming long-run productive capacity and causing structural unemployment.
- Time lags in transmission (often 18 to 24 months for interest rate changes to fully impact consumer behavior and price levels).
- Cannot directly solve structural supply-side problems (such as low labor productivity or supply bottlenecks).

Evaluation and Conclusion:
- Supply-side policies are not always preferable. If the economy is experiencing rapid demand-pull inflation, contractionary monetary policy is a much faster and more direct instrument to cool down the economy.
- If the economy faces low growth due to a lack of aggregate demand, supply-side policies alone will not work without supporting demand-management policies.
- Therefore, the policies should be seen as complementary rather than substitutes. A balanced policy mix is essential for achieving long-run sustainable growth with price stability.

AO1 Knowledge & Understanding and AO2 Analysis [Up to 8 marks]:
- 7-8 marks: Clear, detailed analysis of how both supply-side and monetary policies operate to influence growth and inflation. Accurate AD/AS transmission mechanisms are clearly described. Comprehensive understanding of the mechanisms (e.g., how LRAS shifts vs. AD shifts).
- 5-6 marks: Good explanation of both policy types, but may lack depth in explaining how they manage the trade-off between inflation and growth, or may focus heavily on one policy over the other.
- 3-4 marks: Limited explanation of the policies, containing some errors or lacking logical progression in the transmission mechanisms.
- 1-2 marks: Identification of the policies with minimal economic analysis.

AO3 Evaluation [Up to 4 marks]:
- 4 marks: Thorough evaluation of whether supply-side policies are 'always' preferable. Explicitly considers factors such as the type of inflation (demand-pull vs. cost-push), time horizons (short-run vs. long-run), government budget constraints, and concludes with a clear, well-justified judgment that they are complementary.
- 2-3 marks: Some evaluative comments, such as pointing out the time lags of supply-side policy and comparing them with monetary policy, but lacking a fully developed, balanced conclusion.
- 1 mark: Minimal evaluative comment (e.g., simply stating that one policy is better than the other without strong justification).